Returns the value of the second or third argument depending on the truth of the first argument.
if(expression, true_value, false_value)
This is a function, which means all parameters to the function are evaluated. So something like if($F > 1, system('echo 1'), system('echo 2')) will result in both system calls being run regardless of the result of the expression.
if ($F<12, $F, 75)
When the current frame number (
$F) is less than 12,
returns the current frame number, otherwise returns